We are developing an animal model of simian T-cell lymphotropic virus (STLV-I) induced disease. We originally identified an African green monkey with lymphoproliferative disease and advanced immunodeficiency disease. This monkey was naturally infected with STLV-IAGM and SIVAGM. It developed hyperplastic lymph nodes that arose from the expansion of STLV-I infected and monoclonally integrated cells, immunosuppression and widespread dissemination of a naturally occurring simian immunodeficiency virus (SIVAGM). Serological screening of our rhesus breeding colony has demonstrated an approximate incidence of 15-20% positive for antibodies to STLV-I. The African green monkey colony was similarly screened, but showed a much higher 51% incidence of STLV-I antibodies. The positives were at least at levels 4-5 fold higher than background. We have isolated virus-producing transformed cell lines from a number of these animals and have utilized them for inoculations into naive animals. The animals presently on this study are recipients of STLV-IAGM, STLV-IRhesus, or STLV-ISooty Mangabey. All animals seroconverted, became PCR and culture positive. There was an apparent lymphocytosis, and lymphocyte subset changes in certain of the animals. However, the virus has now become latent, as would be expected in the natural course of the disease. We have been utilizing various treatments (hormone, and immunosuppresion) to stimulate and reactivate the virus. Results to date suggest some success with this approach. We are monitoring longevity of activation,